Table 1 Some important pathways of introduction for non-native terrestrial animals, terrestrial plants, and aquatic organisms

Terrestrial vertebrates

Mammals

Intentional introduction as commodity (for hunting, 'fauna improvement', fur farming, as pets, or for zoos), then either intentional release or accidental escape

[9, 31]

Birds

Intentional introduction as commodity (for hunting, 'fauna improvement', as pets, or for zoos or bird parks), then either intentional release or accidental escape

[9, 32]

Reptiles/amphibians

Intentional introduction as commodity (for 'fauna improvement', as pets, food source, or biological control agents), then either intentional release or accidental escape

[9, 32]

Terrestrial invertebrates

Insects

Unintentional introduction as contaminants or stowaways, sometimes deliberate release as biological control agents

[9, 33]

Other

Unintentional introduction as contaminants or stowaways

[33]

Terrestrial plants

Vascular plants, mosses, and lichens

Intentional introduction as commodity for garden trade (ornamentals), horticulture, unintentional introduction as contaminant of plants introduced for agriculture and ornamental trade (e.g., soil contaminants in plant pots)

[9, 10, 34, 126]

Aquatic organisms

Fishes

Intentional introduction for aquaculture, stocking to improve recreational and commercial fisheries (including illegal stocking), as well as for weed and mosquito control, unintentional introductions with ship ballast water, ornamental species, fishing bait releases

[75, 127]

Crustaceans

Intentional introduction for aquaculture, ornamental reasons (Decapoda), unintentional introductions with ship ballast water, canals

[38, 128–130]

Mollusks

Unintentional introductions with shipping, waterways, accidental (e.g. during fish stocking), but also from garden pond and aquarium trade

[131, 132]

Plants

Intentional introduction for ornamental (aquarium and watergarden) trade, often further spread by boats and waterbirds

[133, 134]